Pressure Control at Variable Speed

In a specific application, a large, mixed hydrocarbon gas system may be set up with a turbine-driven compressor as shown in Figure 8-40(a).

The process demands that a constant pressure be held on the header at various loads (flow). Specifically, the control system operates as follows;

1. The pressure transmitter (transducer block) senses the process pressure. It converts this signal to a signal proportional to the process pressure and sends it to the pressure controller.

2. The pressure controller (controller block) amplifies the transmitter signal and sends a modified signal to the final element. Depending on the system requirements, the controller block may include additional correction factors, integral and derivative (reset and rate). This is called a three-mode controller.

3. The final element in this case is speed control. This mechanism varies the turbine-governor speed setting over a predetermined range.

A pressure rise in the reactor would cause an increase in process pressure above the set value, send a signal to the governor, and thus, reduce the speed, lower the flow, and thereby, maintain the desired system pressure.

Living Off The Grid

Living Off The Grid

Get All The Support And Guidance You Need To Be A Success At Living Off The Grid. This Book Is One Of The Most Valuable Resources In The World When It Comes To When Living Within The Grid Is Not Making Sense Anymore.

Get My Free Ebook


Post a comment